[blink] Request compositing update when canvas hibernates/wakes up.

third_party/WebKit/Source/core/html/HTMLCanvasElement.h

 /*
  * Copyright (C) 2004, 2006, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 186 matching lines @@
   int SourceWidth() override { return size_.Width(); }
   int SourceHeight() override { return size_.Height(); }
 
   // CanvasSurfaceLayerBridgeObserver implementation
   void OnWebLayerReplaced() override;
 
   // ImageBufferClient implementation
   void NotifySurfaceInvalid() override;
   void DidDisableAcceleration() override;
   void RestoreCanvasMatrixClipStack(PaintCanvas*) const override;
+  void SetNeedsCompositingUpdate() override;
 
   // ImageBitmapSource implementation
   IntSize BitmapSourceSize() const override;
   ScriptPromise CreateImageBitmap(ScriptState*,
                                   EventTarget&,
                                   Optional<IntRect> crop_rect,
                                   const ImageBitmapOptions&,
                                   ExceptionState&) override;
 
   // OffscreenCanvasPlaceholder implementation.
@@ skipping 105 matching lines @@
   std::unique_ptr<CanvasSurfaceLayerBridge> surface_layer_bridge_;
 
   int num_frames_since_last_rendering_mode_switch_;
   bool pending_rendering_mode_switch_;
   bool did_notify_listeners_for_current_frame_ = false;
 };
 
 }  // namespace blink
 
 #endif  // HTMLCanvasElement_h